MACPAINT.TXT
Remove Frame
MacPaint description excerpted from:
ST Picture Formats
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Edited by:
David Baggett
Internet:
[email protected]
(Please report errors or additions.)
Copyright (C) 1988 -- 1995 by David M. Baggett
Non-profit redistribution of this document is permitted, provided
the document is not modified in any way.
Reproduction of this document in whole or in part for commercial
purposes is expressly forbidden without the prior written consent
of David M. Baggett.
The information presented here is not guaranteed to be correct.
The editor and contributors will in no event be liable for direct,
indirect, incidental, or consequential damages resulting from the
use of the information in this document.
This document is the product of many hours of volunteer work by a
large number of people. Please respect this -- do not violate the
distribution policy.
CONTRIBUTORS
Steve Belczyk Phil Blanchfield Marcel Boom Jason Blochowiak
John Brochu** David Brooks Daniel Deimert Martyn Dryden
Neil Forsyth Stefan Hoehn Gerfried Klein G. "Maddog" Knauss
Ken MacLeod Shamus McBride Jim McCabe Lars Michael
Darek Mihocka David Mumper George Nassas Jim Omura
Chris Ridd George Seto Joe Smith Greg Wageman
Roland Waldi* Gerry Wheeler
Introductory Information
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word = 2 bytes
long = 4 bytes
palette = Hardware color palette, stored as 16 words. First word is
color register zero (background), last word is color register
15. Each word has the form:
Bit: (MSB) 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 (LSB)
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
0 0 0 0 0 R2 R1 R0 0 G2 G1 G0 0 B2 B1 B0
R2 = MSB of red intensity
R0 = LSB of red intensity
G2 = MSB of green intensity
G0 = LSB of green intensity
B2 = MSB of blue intensity
B0 = LSB of blue intensity
Intensity ranges from 0 (color not present) to 7 (highest
intensity).
Example: { red = 7, green = 3, blue = 5 } -> 0735 (hex)
Caveat: It is wise to mask off the upper four bits of each
palette entry, since a few programs store special
information there (e.g., Art Studio).
<MacPaint> *.MAC
1 long version number [0=ignore header, 2=header valid]
38 * 8 bytes 8x8 brush/fill patterns. Each byte is a pattern row,
and the bytes map the pattern rows top to bottom. The
patterns are stored in the order they appear at the bottom
of the MacPaint screen top to bottom, left to right.
204 bytes unused
-------------
512 bytes total for header
< 51200 bytes compressed bitmap data
-------------
< 51712 bytes total
NOTE: The version number is actually a flag to MacPaint to indicate if
the brush/fill patterns are present in the file. If the version is 0,
the default patterns are used. Therefore you can simply save a MacPaint
file by writing a blank header (512 $00 bytes), followed by the packed
image data.
Bitmap compression:
The bitmap data is for a 576 pixel by 720 pixel monochrome image.
The packing method is PackBits (see below). There are 72 bytes per
scan line. Each bit represents one pixel; 0 = white, 1 = black.
<PackBits Compression Algorithm>
The following packing algorithm originated on the Mac, was adopted by
Electronic Arts/Commodore for use in the IFF standard, and then by Tom
Hudson for use in DEGAS Elite. The algorithm is currently used in
MacPaint, IFF, and DEGAS Elite compressed file formats. Each scan line
is packed separately, and packing never extends beyond a scan line.
For a given control byte 'n':
0 <= n <= 127 : use the next n + 1 bytes literally (no repetition).
-127 <= n <= -1 : use the next byte -n + 1 times.
n = -128 : no operation, not used.
-------------------------------------------------------------------------
* Roland Waldi contributed extensive information on the following formats:
GEM, IMG, Doodle, STAD, Imagic Film/Picture, Art Director, IFF
** John Brochu, ST picture formats guru, provided sage advice and many
corrections to the following formats:
NeoChrome, DEGAS Elite Compressed, Spectrum 512 Compressed,
GEM Bit Image, IFF, MacPaint
Version of...........Sun Oct 30 12:40:13 EST 1994
(Last change: Extended GEM .IMG format updated)
